Solar energy is ideally used in situations where a remote source of power is needed and connection to the grid is too expensive. Some applications of solar energy in remote locations are as follows:
Cathodic protection is a process to protect vulnerable metals against corrosion. This is done using a small negative voltage applied to the metal. Bridges, wells and railway lines (to name a few examples) can be protected against corrosion when a positive terminal is attached to the metal and a sacrificial anode is attached to a piece of scrap metal.
Small solar energy and wind energy systems are used to power many cathodic protection systems. Solar PV panels and even small wind turbine systems along with batteries and other system components will work independently of source energy (wind or sun) for up to a week.
This reliability and economics (much cheaper than running hydro lines to any remote area) make these renewable energy sources a big player in the cathodic protection industry (a $2 billion a year industry in the US).
Trestles, pipelines, steel tanks and marine locations are some other structures protected against corrosion, using cathodic protection.